The present invention relates to an adsorbent for removing lipoproteins in blood and the like, more specifically an adsorbent for selectively adsorbing lipoproteins containing apo-B-protein, i.e. low density lipoprotein (hereinafter referred to as "LDL") and very low density lipoprotein (hereinafter referred to as "VLDL") and to an apparatus for removing lipoproteins.
It has been known that lipoproteins present in blood, especially LDL and VLDL, contain a large amount of cholesterol and cause arteriosclerosis. On the other hand, it has been known that high density lipoprotein (hereinafter referred to as "HDL") is a factor which delays causing arteriosclesrosis.
As a method for removing LDL and VLDL from body fluid such as blood, there has been employed methods using a membrane and using an adsorbent. In the above method using a membrane, a fair amount of HDL are removed as well as LDL and VLDL. Thus it does not satisfy the desired selectivity of lipoprotein. Further, since some plasma proteins are removed at the same time, it is necessary to supply plasma proteins.
With regard to methods using an adsorbent, there are, for instance, a method using an adsorbent wherein an antibody is immobilized, so-called immunoadsorbent, and a method using an adsorbent based on the principle of the affinity chromatography, wherein a compound having an affinity for LDL and VLDL (such compound is hereinafter referred to as "ligand") is immobilized.
Though the method using an immunoadsorbent provides an almost sufficient selectivity, there are many problems such as difficulty for obtaining the antibody, a high price of the antibody, poor stability of the adsorbent when preserving.
In the method based on the principle of affinity chromatography, heparin, dextran sulfate and the like are typically used as a ligand. The adsorbent immobilized with the above ligand has a good selectivity and the ligand employed is not too expensive. However, many of them are difficult to sterilize and it is required to lower the cost for using ligands in large quantities.
There is also an adsorbent, which has an organic compound such as phenylglycidyl ether as a ligand, adsorbing lipoproteins by hydrophobic interaction between phenyl group and the hydrophobic part on the surface of a lipoprotein. As the above adsorbent, there is commercially available Phenyl-Sepharose CL-4B (made by Pharmacia Fine Chemicals AB). While this adsorbent is inexpensive, it has a serious problem in selectivity as it adsorbs not only LDL and VLDL but also large amount of HDL.
The object of the present invention is to provide a low-cost and stable adsorbent which can selectively remove LDL and VLDL from the body fluid.
The present invention relates to an adsorbent for lipoproteins which is a water-insoluble matrix having, on at least a part of the surface thereof, a group of the formula: EQU --NR.sup.1 R.sup.2
wherein R.sup.1 is hydrogen, methyl group or ethyl group; and R.sup.2 is a substituent with an aromatic ring and satisfying the condition that the value of log P, in which P is a partition coefficient in a water-octanol system, of a compound of the formula R.sup.2 ##EQU1## is from 0 to 3.2.
The present invention relates to an apparatus for removing lipoproteins which comprises a container having a fluid inlet and a fluid outlet, filters through which a fluid and components included in the fluid can pass while an adsorbent, which is the above mentioned water-insoluble matrix, cannot pass, and which are provided at both the inlet and outlet, and an adsorbent which is packed in the container.